To further enhance protective control of electrical power distribution systems, intelligent protective relay devices have been developed which are provided with communication capabilities to communicate protective relay data. To date, network communication capabilities have been implemented using data rates of less than 1 Megabits per second, and using RS-485, RS-232, fiber optic asynchronous serial interfaces, or UART interfaces. Typically, communication among networked protective relays has been implemented using "master-slave" protocols, in which certain network devices are prioritized. For example, U.S. Pat. No. 4,972,290 to Sun et al. discloses an electrical power distribution system with remote monitoring and control of protective relays. The disclosed system includes slave stations which continuously monitor activity of analog protective relays, and a master station which communicates with the slave monitoring stations and stores network relay data. The Sun patent also discloses communication of relay data via RS-232 communication channels.
While the desire for protective relays having communications capabilities has been recognized, there are shortcomings associated with known schemes for communicating protective relay information. For example, known relay communication schemes do not adequately address potential problems relating noise (e.g., due to electromagnetic interference) and communication line faults, and do not adequately provide high speed (greater than 1 Mbps) communication capability. Further, the environment in which intelligent protective relays operate is subject to severe conditions, including relatively wide temperature variations, which presents design challenges for potential solutions to the problem of providing a reliable, fault-tolerant, high-speed communications scheme for protective relays.